Patent attributes
A vehicle-mounted engine control apparatus can accurately measure the resistance value of a label resistor arranged in an exhaust gas sensor for correcting characteristic variation thereof by using a reduced number of wires. An electric heater of the exhaust gas sensor, which is powered from a second power supply wire, as well as the label resistor and air fuel ratio measurement elements are connected to the apparatus which is powered from an on-vehicle battery through a first power supply wire. A power feed voltage of the apparatus is input to a multichannel AD converter through voltage dividing resistors, so that a positive end potential of the label resistor is measured alternatively. A negative end potential of the label resistor is input to the converter as a divided voltage thereof with a fixed resistor. The label resistance value is calculated from a fixed resistor current and a label resistor voltage.
